You should make a quality earth ground connection to all Keri PXL controllers to ensure the best possible operating conditions. An earth ground brings all electrically neutral lines to the earth's surface potential (essentially to a zero
potential). Without a quality earth ground connection, the access control system may appear to operate correctly, but can
be extremely susceptible to transients and electromagnetic interference on data and power lines. In addition, while the
system may appear to work correctly now, improper or non-existent earth grounding can cause erratic system reliability in
the future, resulting in possible equipment failure and/or more frequent service calls.
This document refers to the following products:
- PXL 500 controllers
- Entraguard controllers
A proper earth ground provides the following benefits:
- An earth ground protects a controller from electrical transients such as power surges (which also provides a degree of
safety for an installer).
- An earth ground provides a path to ground for electrical interference helping to minimize data and communication
problems for controller to host communications.
Typical Sources of Earth-Ground:
• copper shrouded ground rod
• cold water pipe (must be a metal pipe, galvanized or copper – it cannot be PVC)
• steel building framing member (however, the building's frame must be embedded in the earth)
• electrical system ground (at the breaker/fuse box)
• telephone system ground
Typically an earth ground wire is:
• a single conductor, solid strand, AWG 18 wire (a larger gauge is always acceptable)
• green with a yellow tracer (but are also often solid green)
When making an earth ground connection:
• Each controller should have its own, unique earth ground. Do not daisy-chain earth ground connections between
• When routing the earth ground wire, make it the shortest path to ground as possible.
• Verify a solid earth ground connection has been made before turning on controller power for the first time.
• Periodically verify the quality of the controller's earth ground connection
Make the earth ground to controller connection at:
You should make a quality earth-ground connection to the metal enclosure lug (which displays an adjacent earth-ground symbol).
This good-quality earth-ground at the enclosure lug will provide an earth-ground for the entire enclosure - and will therefore ground anything that is connected to the metal enclosure - (the four metal screws at each corner of the PCB) - plus, through circuitry on the PCB, this includes anything connected to the lug marked J6 or pin 3 of the TB10 power connector.
In addition, the enclosure itself must be earth grounded to a good quality ground point external to the enclosure for a complete path to ground.
Also, the shield/drain wire of any reader/peripheral cables MUST be terminated to one of the following points-any corner screw attaching the controller to the enclosure, Pin 3 of TB10, the green ground lug (J6) on the controller, or the ground lug of the enclosure. Failure to properly earth ground the reader/peripheral drain wire may result in unreliable communication or operation of the attached peripheral.
- The earth ground connection on PXL controllers is made to Pin 3 of TB2 on the controller PCB.
- On the Entraguard, the earth ground connection is made to Pin 3 of TB2 on the controller PCB.